Researchers at MIT have created a new way to track movement through walls, and it is even more accurate and revealing than the motion tracking technology they created in June of this year. It's called WiTrack, and it can sense a person's movements in three dimensions -- physical occlusions or no. It's an update to the same researchers' "WiVi", which could "see" through walls but wasn't nearly as comprehensive as this.

WiTrack is analogous to sonar or radar. It uses a radio transmitter and three receiving antennae. A low-power radio signal is sent from the transmitting antenna, and the other antennae pick up variations in when the signal is bounced back. The system then calculates the differences and actively determines the person's location in real time.

The extra accuracy in this new system is derived from the fact that the signal is 100 times smaller than Wi-Fi and 1,000 times smaller than a cell phone transmitter. WiTrack is accurate to within 4 to 8 inches.

The earlier WiVi used fewer antennae and a standard Wi-Fi transmission, which wasn't as accurate. It also couldn't pinpoint an exact location in three dimensions, only track how far the person was from the receiving antennae.

The researchers suggested a few real-world applications for the WiTrack technology. It could be used in police and emergency teams to track hiding or incapacitated people in a building, for example. It could even be used to detect when someone has fallen to the ground.

It could also be used for gaming: the system could turn a gamer's entire house into a gameplay field with no need for optical line of sight as with, say, a Kinect.